IOSR Journal of Engineering (IOSR-JEN) Volume 4 issue 5

1. IOSR Journal of Engineering (IOSRJEN) www.iosrjen.org
ISSN (e): 2250-3021, ISSN (p): 2278-8719
Vol. 04, Issue 05 (May. 2014), ||V3|| PP 36-41
International organization of Scientific Research 36 | P a g e
Performance Characteristics of a Gasohol Fueled S.I Engine.
Laminu S. Kuburi, David O. Obada, Ibraheem A. Samotu, Chike V. Chira
Obinna A. Osuchukwu and M. Jeremiah.
Department of Mechanical Engineering, Ahmadu Bello University, Zaria, Nigeria.
Abstract: - Ethanol is a renewable fuel which has the added advantage of improving performance in typically
knock-limited operating regions due to the higher octane rating of the fuel. Ethanol was synthesized from
groundnut seeds using fermentation method. An experiment was then designed to run a gasoline engine. In this
work, the effect of ethanol addition to gasoline on the performance characteristics of a spark ignition engine at
various speeds was established. Gasoline was blended with 20 – 80% of the extracted ethanol in an interval of
20%. Results of the engine test indicated that blending ethanol in a proportion of 40% with gasoline can be used
as a supplementary fuel in modern spark ignition engines as it is expected to achieve optimum performance on
the engine.
Keywords: - Ethanol, Gasoline, performance, Spark ignition engine.
I. INTRODUCTION
While ethanol is an attractive option for offsetting dependence on petroleum based gasoline, the
differences in fuel properties between gasoline and ethanol can significantly alter engine performance [1], [2],
[3]. Due to the different molecular structure of ethanol, the stoichiometric air-fuel ratio of ethanol is
substantially different than gasoline and the air and fuel controllers must target different values for ethanol
blends. Ethanol also has a different laminar flame speed than gasoline; therefore, the rate at which flames
propagate during combustion will differ depending on the fuel ethanol content and combustion phasing will be
directly affected. In addition, as a result of its higher octane rating, ethanol has a higher resistance to knock than
gasoline. Ethanol fuel is ethanol (ethyl alcohol), the same type of alcohol found in alcoholic beverages. It can be
used mainly as a biofuel alternative to gasoline, and is widely used by flex-fuel light vehicles in Brazil, and as
oxygenate to gasoline in the United States. Together, both countries were responsible for 89% of the world’s
ethanol production in 2008 [4]. As noted by Blume [5], the following are the key reasons for which ethanol is
attractive as a substitute to gasoline: Ethanol is 98% pollution free; biodegradable; renewable; there is no carbon
left when ethanol burns in cars; ethanol does not cause climate change; and all the by-products in the production
of ethanol are edible and nontoxic, providing a very good source for animal feedstock.
Methanol has also been proposed as a fuel for internal combustion and other engines mainly in
combination with gasoline. Historically, methanol was first produced from pyrolysis of wood. Presently,
methanol is usually produced using methane as a raw material. Both methanol and ethanol burn at lower
temperatures than gasoline, and both are less volatile, making engine starting in cold weather more difficult.
Using methanol as a fuel in spark ignition engines can offer an increased thermal efficiency and increased power
output due to its high octane rating (114) and high heat of vaporization. However, its low energy content of 19.7
MJ/kg and stoichiometric air fuel ratio of 6.42:1 mean that fuel consumption will be higher than hydrocarbon
fuels [6]. Ethanol (CH3CH2OH) is more reactive than hydrocarbon fuels, such as gasoline. Since it is an alcohol,
its molecular structure shows a polar fraction due to the hydroxyl radical and a non polar fraction in its carbon
chain. That explains why ethanol can be dissolved in both gasoline (non polar) and in water (polar). Due to its
short carbon chain, the properties of ethanol polar fraction overcome the non polar properties. The formation of
hydrogen bridges in ethanol molecule results in higher boiling temperature in comparison to that of gasoline.
Ethanol is less toxic than methanol – another alcohol used as fuel. The simple structure of ethanol molecule
makes it suitable for spark ignition internal combustion engines operation. The high octane number of ethanol
allows for higher compression ratios in comparison to gasoline fuelled engines [7] .In Brazil, ethanol is
produced from sugar-cane, a renewable energy source. Sugar cane molasses contains about 40% sucrose, which
hydrolysis by an enzyme called invertase produces glucose or fructose. The enzyme is elaborated by brewer’s
yeast. Ethanol is formed by glucose (C6H12O6) fermentation in the presence of another enzyme called zymase.
This is shown in the equations below;
C12H22O11 + H2O xC6H12O6 + (2-x) C6H12O6 0 ≤ x ≤ 1 ………. (1)
C6H12O6 2C2H5OH + 2CO2 ……………………………….... (2)

2. Performance Characteristics of a Gasohol Fueled S.I Engine.
International organization of Scientific Research 37 | P a g e
Given the foregoing, the objective of this study was therefore to investigate the performance
characteristics of a 2000rpm single cylinder gasoline generator engine using ethanol:gasoline fuel mixing ratios.
II. METHODOLOGY
2.2 Experimental Procedure
2.2.1 Biodiesel Synthesis
Groundnut shells of samnut-38 specie was obtained from institute of agricultural research, Samaru Zaria
and taken to the microbiology laboratory Ahmadu Bello University Zaria for synthesis. Groundnut shells are
agricultural residues and a readily available source of lignocelluloses. This residue was washed with distilled
water and then dried for three days at 600
C in a hot air memmert oven. This was done to reduce the moisture
content and make them more susceptible to milling.
The substrate was milled with mortar and pistil, sieved to pass through a mesh sieve. 1500g of the sample
was weighed and then soaked in 1% (w/v) sodium hydroxide solution (substrate + solution) for 2hours at room
temperature after which it was washed with distilled water and dilute HCL until the wash water was neutral on
PH scale. It was then set in memmert oven (Model UE-500 DINII2880) overnight at 600
C to dry. The
fermentation medium used for the ethanol production consisted of glucose 8%(w/v) peptone 0.1%(w/v), malt
extract 0.1%(w/v), yeast extract 0.2%(w/v), ammonium sulphate 0.2%(w/v) and ferrous sulphate, 0.001%(w/v).
200ml medium culture was prepared and 300ml dispense was added into each 500ml erlenmeyer flask. The
flasks were sterilized in an autoclave (Model Astell ASB 300) at 1210
C for 15minutes at 151bs pressure and
inoculated with 15ml and 4ml containing growth innocula of S. cerevesiae and A. niger cells and 2 million
spores respectively.
The flasks were incubated on orbital shaker (Model vineland NJ SH2-526) with an initial agitation rate of
300rpm at 300
C for seven days. The sample was withdrawn at interval of 24hours for distillation.
2.2.2 Fuel Properties Determination
Fuel properties of tested blends were determined in accordance with American Standard for Testing
Materials (ASTM) procedures for petroleum products.
Each fuel sample was evaluated to determine the density, API gravity, heat of combustion. The density of
each tested sample was measured by hydrometer method (ASTM D287 Standard). The API gravity was
calculated from density results. Heat of combustion was measured in record bomb calorimeter according to
PARR 1266 standards, France (ASTM D240).
2.2.3 Engine Performance Evaluation
A load test was done with gasoline and its blends with ethanol as fuel on the Peters PIAW carburetted
single cylinder four stroke SI engine with maximum speed of 2000rpm.
Figure 1: A pictorial view of the Peters PAIW S.I engine used in this study.
This was done to obtain a set of performance parameters. The performance parameters were calculated using the
following equations:
1. Brake Power
𝐵𝑃 =
𝑊 × 𝑁 × 0.736
𝐶
______________________(3)
Where;

3. Performance Characteristics of a Gasohol Fueled S.I Engine.
International organization of Scientific Research 38 | P a g e
BP = Break Power (KW)
W = weight reading from scale in kg
N = speed of the engine in rpm
C = constant 1000
2. Mass of fuel consumed
𝑚𝑓𝑐 =
𝑋𝐶𝐶 × 0.72 × 3600
1000 × 𝑇
____________________(4)
Where;
mfc = mass of fuel consumed
XCC = Burette reading in mm
0.72 = density of gasoline in gram/mm
T = time taken in seconds
3. Specific fuel consumption
Specific fuel consumption 𝑠𝑓𝑐 =
𝑚𝑓𝑐
𝐵𝑃 ___________ (5)
4. Actual volume of air sucked into the cylinder
actual air volume suck into cylinder 𝑉𝑎 = 3600 𝑥 𝐶 𝑑 𝑥 𝐴 𝑥 2𝑔𝐻 ___________(6)
Where;
𝐻 =
𝑕
1000 𝑥
𝜌𝑤
𝜌𝑎
____________________ 7
d = 20mm
A = Area of orifice = 𝜋𝑑2
4 = 3.14 x 10-4
h = manometer reading in mm
ρw = density of water = 1000kg/m3
ρa = density of air = 1.193kg/m3
Cd = coefficient of discharge = 0.62
g = acceleration due to gravity = 9.81m2
/s
5. Swept volume
𝑉𝑠 =
𝜋𝑑 𝑚
2
4 𝑥 𝐿 𝑥 𝑁
2 𝑥 3 𝑥 60_______________________ 8
Where, Vs = Swept Volume
dm = diameter of the bore = 0.0685m
L = length of the stroke = 0.072m
N = speed of the engine in rpm
6. Volumetric efficiency
𝑉𝑜𝑙𝑢𝑚𝑒𝑡𝑟𝑖𝑐 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 (ŋ 𝑣
) =
𝑉𝑎
𝑉𝑠
𝑥 100______________________(9)
III. RESULTS AND DISCUSSION
The Calorific value, density and Specific gravity of Blends of gasoline and ethanol produced from Groundnut
shell is presented in the table 1 below.
Table 1: Some Properties of Blends of gasoline and ethanol produced.
S/No SAMPLE
ID (%)
GROSS
HEAT
(MJ/KG)
INITIAL
TEMPT.,
(0
C)
FINAL
TEMPERATURE
(0
C)
SAMPLE
WEIGHT
(g)
DENSITY
(Kg/m3
)
SPECIFIC
GRAVITY
1 E0 480.2900 23.7654 26.6705 0.0001 703.5 0.7035
2 E20 459.0304 24.1345 25.4115 0.0001 712.3 0.7144
3 E40 437.6332 23.9650 24.1783 0.0001 724.2 0.7343
4 E60 364.1156 24.9673 25.3214 0.0001 737.9 0.7453
5 E80 230.6436 25.3219 26.5336 0.0001 746.7 0.7467
From the results obtained, it was observed that the gross heat of the blend was decreasing with increase
in the percentage of ethanol added. On the other hand the density and specific gravity of the blend are increasing
with increase in the percentage of ethanol added. This implies that the mass of the synthesized ethanol is higher
that of pure gasoline which resulted in the increase of the blends’ densities.

4. Performance Characteristics of a Gasohol Fueled S.I Engine.
International organization of Scientific Research 39 | P a g e
3.1 Engine Performance Analysis
For the experiment, the electrical load from the dynamometer was varied and the resultant mechanical
load was noted for each sample at various speeds. Tables 2, 3, and 4, given below are for the samples test
conducted. Data were obtained based on the engine operating parameters and instrument readings.
Table 2: Specific Fuel Consumption (SFC) at different Engine Speed
Samples
Speed rpm
E0
(kg/Whr)
E20
(kg/Whr.)
E40
(kg/Whr.)
E60
(kg/Whr)
E80
(kg/Whr.)
1000 0.27 0.31 0.32 0.32 0.34
1200 0.31 0.33 0.36 0.32 0.34
1400 0.32 0.40 0.37 0.36 0.33
1600 0.41 0.39 0.36 0.37 0.33
1800 0.42 0.36 0.35 0.34 0.32
Table 3: Engine Power at different Engine Speed
Samples
Speed rpm
E0
(KW)
E20
(KW)
E40
(KW)
E60
(KW)
E80
(KW)
1000 1.05 1.45 1.55 1.50 1.35
1200 1.25 1.75 1.70 1.72 1.71
1400 1.85 1.95 2.30 2.15 2.10
1600 1.70 2.25 2.70 2.30 2.35
1800 2.05 2.55 2.70 2.60 2.60
Table 4: Volumetric Efficiency at different Engine Speed
Samples
Speed rpm
E0
(%)
E20
(%)
E40
(%)
E60
(%)
E80
(%)
1000 0.44 0.47 0.51 0.50 0.49
1200 0.46 0.52 0.53 0.52 0.51
1400 0.52 0.58 0.62 0.59 0.57
1600 0.53 0.65 0.76 0.71 0.68
1800 0.62 0.65 0.89 0.81 0.76
Figure 2 shows the effect of the ethanol fuel blending on the specific fuel consumption (SFC). The
specific fuel consumption is slightly increased as the volume percentage of ethanol fuel increases in the mixture.
This is due to the lower heating value of ethanol compared with gasoline (Table 2). From the graph, it was
observed that the specific fuel consumption increases as the engine speed increases for control, but rises to a
peak and fall at higher engine speed for the blends. Maximum specific fuel consumption of 0.4kg/Whr,
0.37kg/Whr and 0.37kg/Whr was obtained for E20, E40 and E60 at an engine speed of about 1400rpm for E20 and
1600rpm for samples E40 and E60 respectively. For sample E80, the specific fuel consumption with respect to
speed is almost linear; therefore, approximately constant with only a slight variation for increasing speed.

5. Performance Characteristics of a Gasohol Fueled S.I Engine.
International organization of Scientific Research 40 | P a g e
Figure 2: Effect of ethanol blends on the specific fuel consumption
Figure 3 shows the effect of the ethanol fuel blending on the brake power. As the ethanol content in the
blend fuel increases, power also dramatically increases. This can be associated with higher heat of evaporation
of ethanol compare to that of gasoline. High heat of evaporation can provide cooling for fuel–air charge, hence
its density increases. Thus higher power output is obtained from the blends. However, power increase starts to
decrease when ethanol content is more than 40%. This is due to the lower heating value of ethanol compared
with gasoline (Table 3).
Figure 3: Effect of ethanol-gasoline blends on the engine power
Figure 4 shows the effect of the ethanol fuel blending on the volumetric efficiency. The volumetric
efficiency increases as the volume percentage of ethanol fuel increases in the mixture. The heat of evaporation
of ethanol is about 2.75 times higher than that of gasoline (Table 4), and this reduces the temperature of the
intake manifold, and increases the volumetric efficiency. However, the volumetric efficiency starts to decrease
when ethanol content is more than 40%.
0.25
0.27
0.29
0.31
0.33
0.35
0.37
0.39
0.41
0.43
800 1300 1800 2300
SFC(kg/Whr)
Speed in rpm
E0
E20
E40
E60
E80
1
1.5
2
2.5
3
800 1000 1200 1400 1600 1800 2000
PowerinkW
Speed in rpm
E0
E20
E40
E60
E80

6. Performance Characteristics of a Gasohol Fueled S.I Engine.
International organization of Scientific Research 41 | P a g e
Figure 4: Effect of ethanol-gasoline blend on the volumetric efficiency
IV. CONCLUSION
Experiments have been conducted on a single cylinder petrol engine with different percentage of
ethanol as additive to gasoline in respect to their performance indicating parameters. It is concluded that,
increase in the engine speed causes increase in the rate of fuel consumption for control sample, while it
decreases at higher speed for the blends. Furthermore, increase in percentage composition of ethanol increases
the engine power and volumetric efficiency while the highest engine power of 2.70KW and volumetric
efficiency of 0.76 were obtained from blend E40. Thus ethanol may be used as an additive for gasoline engines.
REFERENCES
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[4] Licht, F.O. World Fuel Ethanol Production. Renewable Fuels Association 2009.
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0.4
0.5
0.6
0.7
0.8
0.9
1
800 1000 1200 1400 1600 1800 2000
Volmetricefficiency
Speed in rpm
E0
E20
E40
E60
E80